This invention is directed to an energy efficient method for producing alimentary pastes. The terms "alimentary pastes" and "pastes", as used herein, refer to the flour and water mixtures commonly known as pasta, such as spaghetti, macaroni, noodles, ziti, etc.
Alimentary pastes are generally made from coarse, hard flours obtained from hard wheat such as the middlings of durum wheat, often referred to as "semolina flour" or "semolina". Semolina comprises a major portion of the flour in alimentary pastes because it is highly glutinous and provides a self-supporting pasta. Shaped products made therefrom will substantially maintain their original form after subsequent processing, such as cooking. The term "cooking", as used herein, refers to the process of gelatinizing the starch and denaturing the protein to form a firm, rigid matrix within the alimentary paste, which occurs upon heating the alimentary paste.
Pastas are commercially available in many forms including cooked, partially cooked and uncooked forms. Cooked pasta is defined herein to mean pasta wherein substantially all of the starch is gelatinized. Uncooked pasta is defined herein to mean pasta wherein a major portion of the starch is ungelatinized, i.e., greater than about 80% by weight of the total starch content is ungelatinized. The term "uncooked pasta" includes pasta wherein none of the starch is gelatinized. Starch gelatinization is generally accompanied by protein denaturation. Although protein denaturation is of greater concern, starch gelatinization can be quantified with greater accuracy and is therefore used herein to define cooked and uncooked pasta.
There are advantages to each of these types of pasta products; however, the most common form of pasta that is purchased at retail is dry and uncooked pasta. This form is the most versatile in that the product may be stored at room temperature for long periods of time. In addition, pasta in this form maintains its highly glutinous properties in that a substantial portion of protein is undenatured, providing a firm paste upon cooking. Partially cooked and cooked pastas provide the advantage of rapid preparation but often require special packaging, exhibit reduced firmness and product quality, and often have a shorter shelf life than uncooked pasta.
Processes for the commercial manufacture of dry, uncooked pasta are well known. In these processes, water and semolina flour are mixed within an extruder to provide the alimentary paste. This paste is forced through holes in the extruder die at a high pressure and at an elevated temperature, to obtain the desired cross-sectional shape. The extrudate is often cut to desired lengths. In a conventional pasta extrusion process, the alimentary paste exhibits a moisture level of about 30 weight percent and is maintained at a temperature of about 120.degree. F. (49.degree. C.). Moisture levels of about 30 weight percent are utilized to maintain the viscosity of the alimentary paste sufficiently low to prevent excessive pressure within the extruder and simplify the blending procedure. Temperatures of about 120.degree. F. (49.degree. C.) have been utilized to prevent cooking, i.e., gelatinization of the starch and denaturation of the protein within the alimentary paste. Utilizing high temperatures and low moisture pastes in extrusion processes to produce cooked alimentary pastes is known. For example, Bauman, U.S. Pat. No. 4,044,165, and Fulger, U.S. Pat. No. 4,568,550 , each disclose the production of pre-cooked pastas by extrusion techniques where temperatures above 120.degree. F. (49.degree. C.) are utilized. O'Keefe, Food in Canada, pages 16-19 (Jan. 1979), discloses the use of low moisture pastes in producing cooked pasta.
Drying is the most time consuming step in the preparation of uncooked pastas. The extrudate generally has a moisture level of about 28 weight percent or above which must be reduced to a value of about 12%-14% to permit storage of the product at ambient conditions. The drying step, or steps, may require from about 18-36 hours. Since the pasta is in its final extruded shape, drying is a very delicate operation. Accelerating the drying process may affect the integrity of the finished product in that the pasta may warp or crack.
Reducing this drying period without affecting the integrity of the pasta product is advantageous when producing dry, uncooked pasta, since the energy expended is significantly reduced, thus reducing the cost of production.
Craig et al., U.S. Pat. No. 3,762,931, disclose a method for processing low moisture alimentary pastes wherein modifying agents (flow modifiers) are added in significant quantities to reduce the pressure within the extruder. However, it is desirable to obtain shaped, low moisture alimentary pastes wherein the paste composition is not modified significantly to enhance processability. A product with these flow modifiers may not satisfy the definitions ("Standard of Identity") necessary to permit the pasta product to be marketed as "macaroni", "noodles", etc., under Food and Drug Administration Regulations, 21 CFR Chapter 1 .sctn..sctn.139.110-139.180 (Apr. 1, 1986).